Rotary air or gas pump.



L. H'. ROGERS. ROTARY AIR 0R GAS PUMP. APPLICATION FILED MAR. 30, 1906. v 944,91 3. Patented Dec. 28, 1909.

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Patented Dec. 28, 1909.

L. H. ROGERS. l ROTARY AIR 0R GAS PUMP.

Patented Dec.28, 1909.

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L. H. RGERS. ROTARY AIR 0R GAS PUMP. .APPLICATION FILED MAR. ao, 1906.

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Patented Deo. 28, 1909.

L. H. ROGERS.

ROTARY AIR 0R GAS PUMP.

APPLIOATION FILED MAR. 30, 1906.

944,91 3, Patented Dec. 28, 1909. WETS-SHBET 5.

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L. H. ROGERS.

ROTARY AIR 0R GAS PUMP.

APPLICATION FILED MAR. 30, 1906.

Patented Dec. 28, 1909.

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'To all whom it may concern:

LEBBEUS H. ROGERS, 0F NEW YORK, N. Y.

ROTARY AIR 0R GAS PUMP.

Application filed March 30, 1906. 'Serial No. 309,001.

Be it known that I, LEBBES ROGERS, of New York; N. Y., have invented anew and useful Improvement in Rot-ary Air or Gas Pumps, which invention is fully set forth in the following specification.-

This invention relates to air and gas pumps and more particularly to pumps of the rotary type. l

While the invention is specially adapted to compression of gases, yet it may be used as a simple pump, or asa vacuum pump.

In prior applications I have described air and gas pumps of the rotary type in which cam-operated pistons are made to reciprocatein radially disposed piston channels Within a drum revolving within a casing against the inner walls of-w-hich the periphery of the drum or its ends bears snugly. The pumps of the character here referred to have their cut-os in the bearing surfaces of the drum and casing requiring great nicety of fit of the parts, particularly of the drum within the casing. With such close fitting there is necessarily a large amount of friction, and further,.pumps of the kind referred to, in which radially moving pistons take in air during one partof the revolution of the drum and expel the same against reservoir pressure during the remainder ofthe revolution, exert on their shaft-bearings a greater pressure during the compression stroke than when the pistons are idle or are taking in air. In my application Sr. No. 231,800, filed November 7 1904, I show and describe means fbi' applying an equalizing oil pressure to the shafts of the piston-drum within the shaft-bearings to counteract such unequal pressure and to thereby reduce friction at the bearings, and such means are not herein claimed.

The object of the present invention is to eliminate to a large extent the' friction '1ncident to the previous constructions; to provide improved means for balancing or olfsetting the pressure on the shaft-bearings; to secure more uniform action of pistons and to improve the construction of the pump in general.

With these objects in view the invention consists in a closed casing within which a drum having a hollovsT shaft is mounted to revolve in bearings in the casing, both the periphery of the drum and the end walls of the same being out of frictional c ontact with the walls of the casing. The piston-carryingdrum which is preferably made of a single casting is provided with a plurality of radially disposed piston-channels communicating'with the atmosphere through the hollow drum shaft by way of valve-conspeciaeation of Letters ratent. Patented Dec. 28, 1909.

trolled passa es preferably through air-receiving cham ers within the body of the drum. The air-chambers in the drum may each communicate directly with the hollow shaft or may communicate with each other and then have a common connection with said shaft through which the air-or gas to. be compressed or exhausted is taken. Within the piston channels are a plurality of pistons mounted on piston-bars having camrollers running in cam-groovessunk in the end walls of the casing which impart a reciprocating movement to each piston as the drum revolves. Air is taken inthrough the hollow drum shaft from the outside of the casing, during the in-stroke of the pistons,`

passing through the air-chambers to the pis-- tonchannels past pop or check valves. On the compression stroke 'the air is expelled from the piston-channels through valve-controlled outlets.. These valved outlets for the compressed gases may be located in the pistons or in the walls of the piston-channels, and open into the space of the casing through any part of the drum surface. The backs of the pistons are at all times subjected to fluid pressure within the casing or toreservoir pressure, the space behindA the pistons being in open communication with the interior of the casing, through centrally disposed openings near the drum-shaft and preferably filled with some liquid such as oil. Aportion of each piston-face on its air pressure side is preferably subjected to the atmospheric pressure in the air-chamber during the complete cycle of its operations, thereby securing contact of the cam rollers against the outer cam track and avoiding clattering noises in operating the pump, as set forth in my application Sr. No. 299,968, tiled February 7, 1906. i

During the operation of the pump the pistons during their compression stroke exert a force which 'is transmitted to the drum shaft`actin to press the ends of the shaft against its earings. The direction of this for'oe or thrust is radially outward and on the pressure7 side of the drum, increasing as the compression in the piston-channels increases, and resultingin uneven wear of the bearings and increased friction. To offset or roo l4, 5 and 6 show in part elevation section other forms of shield vembodying the balance this pressure of thrust of the shaft on its bearings, I provide one or more pressure, shields which may assume various forms depending on the character of the pressure of the pistons as indicated -by a pressure card, and which are supported by and extend from the inner walls of the casing and rest over and in contact with delinite areas on the surface of the piston drum, to shield such areas from fluid pressure within the casing. The areas of these shields depend mainly on the area of the working piston surfaces, and are so positioned relatively to the drum circumference that the fluid pressure within the casing will off-set or balance the force of the compression stroke of the pistons which is exerted on the shaft bearings.

The invention further resides in providing the pump with means ,for-taking care of the oil which incidentally escapes past the bearings of the piston drum and to return such portions of oil back to the body of oil within the casing against the pressure therein.

The invention further resides in providing an improved cam-track which enables the pistons to reciprocate in their channels with greaterv uniformity of movement, giving to the pump a smoother action.

My invention further consists and-resides in the construction and combination of co` operating elements hereinafter to be more fully described and then recited in the claims which are hereto annexed.

For the purpose of assisting in the description of the invention reference is had to the accompanying drawings, which illustrate certain mechanical expressions of the inventiveidea involved, in which- Figure 1 is a central longitudinal section of the air and gas pump on line 1 1, Fig. 2, and Fig. 2 is a central cross-section on line 2 2, Fig. 1. Fig. 3 is a view in elevation showing one form of pressure-shield. Figs. and part inventive idea. Figs. 7, -8 and 9, illustrate in part elevation and part section various applications of the pressure-shield to the piston drum. Fig. 10 is a view showing another' form ofpiston drum, the broken section being taken on line 10-10, Fig. 11; Fig. 11 is in part an end elevation of the drum shown in Fig. 1'0 and in part a section taken on line 11-11, Fig. 10. Fig. 12 is a diagrammatic view of the drum of Figs. 10 and 11, showing the arrangement of airchannels, and Fig. 13 shows in elevation one of the end walls of the pump casing provided with my improved form of cam track.

Referring to Figs. 1 and 2 the pump casing consists of a cylindrical body portion' 1, having end walls 2, 2, one of which may be integral with said body or both may be preferably cylindrical in shape, in which pistons 7 are caused to reciprocate by means of piston-carrying bars 8, secured thereto, as

by screws 9, said bars extending through longitudinal central spaces inthe drum casting and being provided at their ends with trunnions carrying rollers10,running in camgrooves or tracks 11 formed in the end walls 2, 2, of the casing. These cam-tracks may assume circular or other forms, as will hereafter be more fully described. Those shown in Figs. 1 and 2 referred to are c-ircular.

The outer ends of piston-channels 6 are closed by screw-plugs V12, having a central channel 13, Fig. 2, in which reciprocates a plunger 14 fast in piston 7. The plunger channels are in communication at all times with the atmosphere through passages 15 1.6 and air-chambers 17, thereby exposing a portion of the working piston-face of each piston to atmospheric-pressure during a complete revolution of the drum. The construction just referred to forms a part of the subject-matter of my prior application Sr. No. 299,968, filed February`7, 1906, and is not herein. specifically claimed.

In the present form of the `invention the piston-drum 5 is closed at its ends except near the central portions, where openings are provided for play of the piston-bars 8.

The ends of the drum are held away from the cam-faces formed by the end walls` of the casing to avoid frictional bearing against the cam-faces. This is preferably eected by means of ringsor washers 20 interposed between the drum and cam-faces on the shaft 4. On the pressure-stroke of the piston the air is forced out of the piston-channels 6 through pop valves 19. As-shown in Figs. 1 and 2 these valves are located in the plugs 12 closing the piston channels, but may be located in the piston itself, discharging into the oil-spaces in the axis of the drum,

or they may be located in any other portion of the drum.

` For the purpose of admitting air to the air-chambers 17 which are disposed intermediate the piston-channelsfgfand extend longitudinally of the drum, an air-duct 21 is provided in the shaft 4 of the drum. This duct communicates with the atmosphere by way of an air-inlet chamber 22, formed by a lcap 23 taking over a screw-threaded hub or bearing 24. In the wall of this chamber is located a valved inlet-pipe y25, the valve -therein opening inward, thereby further premitted to the closures 12 and to the drum-l venting escalpe of compressed air by backpressure wit in the drum. The air-duct 21 preferably extends only part wayl along the drum-shaft, as shown in Fig. 1, where it terminates in a small oil-passage 25', the purpose of which is hereafterl fully described. Branching from air-duct 21 are radial airducts 27 Figs. 2 and 10 which communicate with air-chambers 17, and thence to the piston-channels 6 and plunger channels 13 by wayof passages 16, 15 and inwardly-opening pop-valves 18 in the plugs 12. The chambers 17 may have a single air-supply passage 27, in which case the several airchambers 17 will communicate with each other through the VWallsof the drum, as in` my application Sr. No. 299,968, above referred to.l The air-channels 27 in the drumcasting, it will be noted, register with similar openings in the drum shaft 4. In order that there may be no leak at such junction and in order to maintain a proper registry of these channels 27 with the openings in the shaft,

` a screw-threaded bushing 28, Fig. 10, is introduced through channel 27 and inserted into threaded portions of the drum casting and wall of the shaft 4. The outer ends of channels 27 open through the periphery of the drum and are closed by means of screwplugs 29.

By reason of the construction above described whereby the air is admitted through the drum-shaft the ends of the drum are enabled to move out of contact with any bearing surfaces and thereby greatly avoiding frictional resistances and simplifying the construction of the pump.

A' further feature of the invention resides in the manner of balancing the `pressures exerted on the shaft bearings during the compression stroke of the pistons. As illustratedv in Fig. 2 the drum carrying the pistons rotates contra-clockwise, taking in air into the piston-channels 6 on the left-- hand side of the drum from the time the upper piston is moving from its top initial position till it has arrived at a pointf180 therefrom. During the next half revolution the same pistons are compressing air 'against reservoir ressure or pressure within the casing and nally expelling the same through the oil in the casing when the pressure within the piston channels exceeds that of the reservoir pressure. The pressure exerted on the gases within the piston-channels is transshaft 4 against the shaft-bearings 24: on the compression side of the drum, thereby causing friction and unequal wear of the, bearings. To balancebr off-set this thrust -or pressure on the bearings I provide pressureshields 30, Figs. 1 and 3, which extend from the end walls of the casing inward over the drum and conform to the cylindrical ,outlines of the drum with which it contacts.

' illustration a fixed pressure-shield,rectangu- The contour ofthe shield is more or less rectangular and the two, one at each end of the drum, have a total area approximately that of the combined area of the faces of the working pistons. The shields in Fig's. 1 and 70 2 are so positioned about the drum relatively to the working-pistons therein that they shield that portion of the periphery of the drum from external fluid pressure or reservoir pressure opposite that of the comprassion side of the drum. The shielding sur-, face is alsol distributed so that as'the compression within thepiston-channels increases the protecting surface of the shields increases, thereby permitting the Huid-pressure within the casing of the pump to progressively balance or of-set the pressure on the shaft-bearings.

Although I have here described by `way of lar in shape andv positioned to act against the peripheral surface of the drum, it 1s obvious that the shields may be made adjustable or take on other configurations to follow the pressure diagrams or -cards characteristic of the pressure-stroke of the piston, and may take other positions relative to the pistons, and that the shields may guard inner `slurfaces of the piston drum, as shown inv Fig. 8. In lthis form of construction the shields are located on the pressure side' of the drum in order to off-set the pressure on the bearings. The pressure-drum is provided with a run* 31 extending beyond the ends of the drum I and taking over the shield 30 extending 100 from the end walls 2, 2 of thepump casing. The drum 5 rotates in the direction of the arrow and the compression takes place onA the shield side. The off-setting pressure is exerted upward and toward the atmosphere side of the drum on the inner rim 31.

In Fig. 9 another expression of the inventive idea is shown, in which thewalls of cylindrical casing 1 fit against a portion of the piston-drum constituting shields 30". 110 The dome for oil in such case is preferably I formed integral with fthe casing of the pump. `The preferred arrangement, however, for the shields is that shown in Figs.v 1, 2 and 7, in which the pressureshields rest 115 in ledges of the drum substantially flush with the outer surfaceof the same, the form ofthe shieldsbeing more or less rectangular and inshape of wings extending from the end walls ofthe casing and about half-way around-the circumference, as shown in Figs.

1 and 7. It will be lobvious however, that the contour of the shields may be varied and take in other form to meet varied requirements in characteristics of the pistons, as

otherwise protected, is subjected to equal pressures over its entire outer surface. This balance of pressure may, however, be dlsturbed by shielding the surface of the drum from such [pressure by the use of pressureshields vabove described.` A pressure can thus be exerted on the surface of the drum opposite the shields, which is utilized to ofset that of the shaft against its bearings and the point of application oflthis balancing pressure is'made effective at any point by proper location of the shields.

A further feature of my invention resides in the means for taking care of the leakage of oil at the bearings or ends of the shaft and returning the 011 to the interior of the casing against reservoir pressure. Referring to Figs. 1 and 2, the shaft 4 is providedv with an oil duct 25 opening at one end into the air-duct 21 and at its opposite end into a chamber 22 formed by a cap 23 taking over the hub or bearing 24;. Shaft 4 passes throu h the end wall of cap 23 and makes a snug t therein by means of a packing-box of any well-known type.

From the above description it will be clear that oil finding its way from the interior of the casing into chambers 22, 22 will be drawn into ducts 21 and 25 on the suction stroke of the pistons aided by centrifugal force, and will pass by way of passages 27, where` it will be acted on artly by suction and partlyr by centrifuga? force, and will .enter air-chambers 17, there to be further acted on by centrifugal force and impelled p against the outer walls of said chambers. It.

is to be noted that these chambers are preferably located with their outer walls nearer the center'of the drum than are the passages l5 in the piston-channels 12. This position of the chambers relative to the passages 15 coupled with the fact that the drum rotates counter-clockwise combine to impel the oil along the channels 16 toward the pistonchannels 6. The channels 16 are shown as opening tangentially to the outer wall of chambers 17, yet the may open at any other point, if desired, an conduct the oil to channel 15, where it is delivered with the in-going air past valves 18 into the iston-spaces 6. On the compression stroke of) the pistons the escaped oil is expelled with the compressed air against reservoir pressure into the casing of the pump past pop-valves 19.-

In cold weather, whenloil is used within the pump and is permitted to remain for extended periods of time at low temperatures, it sometimes thickens or congeals and impedes starting ofthe pump. To overcome,

this' diicultv I provide i'n the walls of the casing, pre erably at the lower portions thereof, one or more heating chambers 31. vlVithin these chambers I place heating terminals 32 for connection with a source of current. The heating wires can be inclosed in sealed tubes and placed within the cylinder or within the drum itself.

In Fig. 13 I have illustrated a cam-track which iscapable of giving tol the pistons a rectilinear movement in their channels, and such that these movements shall be uniform both during the compression stroke and air intake stroke. To secure this result the track is composed of two separate tracks meeting in a line 40, 40 to form a closed curve. These two branches follow the line of a double spiral along which the trunnions of the pistons advance and give to the pistons a uniform motion along the piston channels as the drum uniformly rotates about its axis.

- The movement imparted to the pistons by this cam track is more uniform than Vinthe case of the circular track and possesses for certain kinds of work advantages over the circular form.

The operation of the device as thus far described will be readily understood from the above description. The several parts of the pum having been assembled and power applie to the shaft 4 in the direction indicated by the arrow, pistons 7 on the lefthand side of the drum, Fig. 2, will move inward and cause air or gas to enter air-duct 21 of shaftfl through Ivalved pipe 25 and chamber 22. 'Ihis air will then pass by way of channels 27, air-chambers 17, ducts 16, 15, past pop-valves l8 to the piston-channels 6. Air will also enter plunger channels 13 which are at all ltimes subject to the pressure of the air in chambers 17 .f As the pistons 7 enter on their compression stroke pop-valves 18 close and the air becomes compressed in piston-channels 6 in the right-hand side of 105 the drum. lVhen this pressure slightly exceeds the pressure-within the space of the l caslng the pop-valves 19 open and the air is forced outward to add its pressure to that in the reservoir. During this compression the p1stons, as previously explained, exert through the shaft a thrust on the bearings which in the illustration, Fig.' 2, isupward and to the right. TOof-set this `pressure and to graduate the balancing pressure to the increasing pressure of the pistons the shield 30 protects va gradually increasing area over the drum, thereby enabling the reservoir 1pressure on the upper right-hand portion o -the drum to off-set the opposing l20 thrust of the shaft in its bearings.

Any oil which escapes past the bearings is caught in chambers 22, 22', and is -drawn into the interior of the shaft by the inward movement of the pistons, and after once en?. tering the radial passages isaided by cen-` trifugal force to move outward into cham-- bers 17 and into the piston channels 6, as previously explained. From the piston channels the escaped oil is forced by the out- Weather that supplemental heating is necessarv. Y

In Figs. 10, 11 and 12 is illustrated another arrangement of the air intake valves and air-channels suitable for use when all the air is delivered directly to the pistonch'annels'and the plungers 14 areomitted. Within the air-chamber 17 is laced a popvalve 33 which is readily intro ud into the chamber by removal of plug 34:, and is secured in the end of the chamber by means of a suitable threaded connection. The leasing of valve 'communicates through ducts 34, 35 and 36 directly to the piston-space, Fig. A11. The operation of this form of the device will be readily understood from what precedes.

In order to reduce the unequal Wear of the cam path at different portions of the same,

i bearin I may vary the form of the path from that illustratedin the drawings as by shorten-- ing the path on the compression side of the drum and lengthening the path on the atmosphere side, whereby the revolutions of the bushings may be equalized infr passing over different portions of the same.

What is claimed is:

1. In a rotary air or gas pump, the combination of a casing, a revoluble shaft having in the walls of said casing, a piston carrying drum mounted on said shaft and a pressure shield over a portion of the drum surface for relieving the fluid pressure inthe casing on said surface, and balancing the fluid pressure Within the casing against the thrust of the shaft on its bearings.

2. In a .rotary air or gas pump, the combination of a casing, a plston ca drum in said casing, a revoluble shaft for said drum `and a pressure shield over a portion of the drum surface for reiieving the fluid pressure in the casing on saidsurface and balancin said pressure against the thrust of the said shaft. A

3. In a rotary air or as pump, the combination of a casing, a rum in said easing having counter-sunk ends, pistons in ysaid drum, a revoluble shaft on which the drum is mounted and a shield for relieving-the fluid pressure in the casing on a portion of said drum and balancing said pressureY against the thrust of the said shaft.

4. In a rotary air or gas pump, the combination of a casin a drum therein having piston channels an pistons therein, a shaft v revolubly supportin said drum out of contact with the Walls o said casil, and a presof e drum sur-- sure shield over a portion 4channels and pistonsv in the sam'e and 'face for relieving the fluid pressure Within the casing on said surface and balancing said pressure against the thrust of said shaft.

5. In an air or gas pump, the combination ofla casing, a revoluble drum in the same out of contact with the casing having piston channels and pistons therein, shaft bearings in opposite Walls of said casing, a revolu le shaft provided with an air supply duct and having its ends supported in said bearings and fast to said drum, valve-controlled said piston chanpassages connecting nels with said air duct and with the interior of said casing. v

6. In. an air or gas pump, the combination of a casmg, a drum in the same having piston channels and pistons therein, and having air chambers communicating with said channels through valve controlled passages, a shaft revolubly supporting said drum out of contact with the Walls of the casing and provided With an air supply duct in communica-- tion with said air chambers and valve controlled outlets for said piston channels.

7. In an air or gas pump, the combination of a casing, .a drum therein having piston rovided with one or more radially disposed) air passages in communication with said piston channels, a shaft revolubly supporting said drum out of contact with the Walls of the casing and provided with an air supply duct, said duct having side openings registering with said radialpassages and bushings in said passages entering saidshaft openings.

8. In an air or gas pump,.the combination of a casing, a drum therein having piston channels andpistons therein, a shaft revolubly supporting said` drum out of Contact with the walls of said casing and provided with an air supply duct in communication with said piston channels, and a semicylindrical pressure shield varying in Width from end to end, having its axis coincident with that of thedrum, said shield being located over a portion of the drum area opposite the compression side of thc drum. Y

y9. In an air or gas pump, the combination of a casing, a drum therein having piston channels and pistons therein, removable plugs closing said channels and ,provided with tivo valve-controlled passages, one passage constituting an air inlet and the other a compressed air outlet,"air`chambers`in said drum communicating with said piston channels through said air :inlet valves, a shaft revolubly supporting said drum out of contact with the wallsof said casing and provided With an air supply duct communicating with said chambers.

10. In an air or gas pump, the combination of a casing, a drum therein having piston channels and pistons in the same, removable plugs closingsaid channels .and provided Wit plunger channels and piston actuated of a casing,

plungers therein, said plugs also being provided With two valve-controlled passages, one passage constituting an air inlet to the piston channel and theother a compressed air outlet for the same, air chambers in the drum having communication with the piston channels through said air'inlet valve and in open communication with said plunger channels, a shaft revolubly supporting said drum and having an air supply duct in communication. With said air chambers.

11. In an air or gas pump, the combination ardrum therein having piston channels and pistons in the same, a shaft for revolubly supporting said drum, having bearings in the Walls of the casing, and provided With a duct extending tothe outside of the casing through both bearings, caps over the ends of the bearings constituting chambers communicating with said duct and serving to trap oil escaping through the bearings and passages in the drum leading from said duct to said piston channels whereby esl caping oil may be returned to the interior of the casing.

12. In an air or gas pump, the combination of a casing, a drum therein, a shaft revolubly supporting said drum, having bearings in the Walls of the casing and means for returning oil escaping at the bearings to the interior of the casing through said drum.

13. In an air or gas pump, the combination of a casing, a drum therein having` piston channels and pistons in the same, said drum having air chambers and. channels tangential to the outer Walls of said chambers and communicating with said p iston channels, a shaft revolubl)r supporting said drum and provided with a duct extending longitudinally` of the shaft and to the exterior of the casing and communicating Withsaid air chambers, and oil traps receiving escaping oil at the bearings and opening into said duct.

14. In an air or gas plump, the combination of a casing, a piston carrying drum mounted -to rotate in a bath of oil in said casin the latter being provided in its Walls with a heating chamber and means in the chamber lfor heating the same, said chamber being located near the bottom of the casing. In testimony whereof I have signed this specification in the presence of two subscribing Witnesses.

- LEBBEUS H. ROGERS. Witnesses:

HIRAIM D. ROGERS. A. I). Espia; 

